Clásico Estados Unidos del Brasil (1952) Sideral (1948–1974) was an Argentine-bred thoroughbred racehorse and is a Classic Chef-de-race.
[1] Seductor, Sideral's sire, was a high-class racer, having been an Argentine Champion Three-Year-Old Colt and counting among his wins the Gran Premio Nacional, Gran Premio Jockey Club, Clásico Comparación, Clásico Miguel Cané, and Cláisco José B. Zubiaurre.
At stud, although he never led the Argentine general sire list, Seductor was on it fourteen times.
[1][2] When Seductor was purchased from Caballeriza Buarque de Macedo by Haras Chapadmalal, an agreement was made that Buarque de Macedo would be able to pick among Seductor's yearling colts, and he chose Sideral due to his early promise.
[4] Sideral was noted for stamping his progeny with both his physical appearance and his high-strung temperament.
[1][2] Victorica Roca, leading Argentine breeder and owner of Haras Ojo de Agua, disliked Sideral as a sire, considering him to produce just winners rather than horses for the classics.